Brake testing apparatus



Oct. 24, 1933. H. SEMMES BRAKE TESTING APPARATUS Filed Dec. 22, 1930SI1/wen to@ #Wa/ar H5N1/755 (lum uuid Patented Oct. 24, 1933 toBendix-Cowdrey Brake Tester, Inc., South Bend, Ind., a'lcorporation ofDelaware Application December k22'1930 v serial No. 504,112

4 claims. (ci.l vri-.51V

This invention relates to the testing' of brakes,

especially the brakes of rautoxr'iobiles and similar vehicles, and 'isillustrated as embodied in test-l ing mechanism of the type in which anlautomo` 5 biley is supported ^by its road 'wheels and the wheels areturned against theresistance of their brakes. 'In one form ofL such amachine, an inertia mass', such'as a fly wheel, is runup to apredetermined speed'v and is then employed to drive any desired group ofwheels againsttheir brake resistance, thus vsimulating the'inertiaeffeet of the car on the road in continuing its motion after the brakesare applied.

An object of the invention is to provide for weights, by varying oradjusting the inertia eect of the wheel-driving mass, for example, byvary,- ing the moment of inertia of the ily wheel or an equivalentrotatable member. Preferablythis is done by adjusting radially of thefly wheel a series of symmetrically-arranged weights.

A further object of the invention is to provide means for testing anydesired group ot wheels of the vehicle tested, such as the rear wheels,front right front wheel and left rear wheel, thewheels on the left ofthe vehicle,`or the wheels on the right of the vehicle. The brakingeffect of the pairs of wheels just enumerated is particularly importantwhen the braking system is partially disabled. Such 1 partialderangement of the braking system may leave only the rear wheels. thefront wheels, the right front wheel and left rear wheel, or the leftfront wheel and right rear wheel effective. Moreover, if the Wheels onone side of the car are on a slippery surface, only the brakes on thewheels of the lother side will be effective. The brake tester hereindisclosed is particularly suitable for testing the brakes on such setsof wheels, in simulation of the braking effect of a partially derangedbraking system.

The above and other objects and features of the invention, including anovel fly wheel,con struction and other desirable structural features,45iwi11 be apparent from the following description Y of one illustrativeembodiment shown in the accompanying drawing, in which: g

.Figure 1 is a top plan view of the apparatus;

Figure 2 is a section on the line 2,'-2 of Figure g 1, showing the novelily wheel;l and Figure 3v is a partial elevation llooking in thedirection of -the arrows 3=3 in Figure 2, and showing the'mounting ofoneof the weights. The apparatus of Figure 1, except for the addition ofmy improvements as described below,

simulating the inertia eiect of cars of different.

wheels, left front wheel and right rear wheel,

' miles an hour,

ltionthis moment of inertia ismade adjustable to weights.

may be and is sho'wn as being the samel as fully described and claimedin application No. 276,294, filed May 9,- 1928, by Furber I. Marshall.This apparatus includes stationary wheel tracks 10, and a movablyadjustable carriage having vtracks 12, `so thatan automobile may be runontor the machine under its own power. There are two rolls 14 forsupporting yand driving the front wheels and which are mounted in theframework of the machine, and two rolls 16 for supporting 65 and drivingthe` rear wheels and which are mounted onthe adjustable carriage betweenthe tracks12.; l y I Rolls 14 and 16, and thereforeA the wheels of theautomobile, are driven through clutches 17 and suitable shafting 18andw19, or the like from an electric motor 20 acting through achange-speed gear 22 and a clutch 23 cooperating with a novel wheel 24more fully described below. Adjacent each roll is a force-measuringdevice S through which the shafting 18 drives the corresponding l roll14 or 16, and which serves to measure the resistance of thecorresponding one of the brakes when the motor is driving the rolls atlow speed.

After the individal effectiveness of the brakes has been checked in thismanner, and any necessary adjustments made, it is the intention to shiftgearing'22 into high speed position and speed up the wheels and flywheel 24 to a known speed equivalent to a road speed of say twenty orthirty and then test the stopping ability of the car (i. e.; theeifectiveness of the entire braking system) by simultaneously applyingthe brakes and throwing out the clutch 23 and then measuring by meanssuch as a counter T the number of rotations of the wheels before thebraking resistance overcomes the inertia of the fly wheel 24 and bringsthe road wheels and rolls 14 and 16 to rest. This result is readilyconvertible into linear. feet of stopping distance at the speed used.

It will be observed that the effect of the momentum of the car whichisovercome by the braking resistance in stopping on the 'road is heresimulated by the moment of inertia of fly wheel 24. According to animportant feature of the invensimulate the inertia effect of cars ofdiierent The provision of the clutches 17 provides for a selectivetesting of' any desired group of wheels, to simulate the braking eilectof a partially disabled braking system. Usually such groups will consistof pairs of wheels, though of course any three of the wheels, or anysingle wheel may be so tested.` The method of testing such groups ofweights is substantially similar to that of testing all four wheelsdescribed in the two preceding paragraphs, except that the clutches 17connected to the rolls 14 or 16 driving the wheels it is not desired totest, are thrown out.

Thus, if it is desired to test the rear wheels only, the clutches 17communicating with the rolls 14 are thrown out.

As best shown in Figure 2, the ily wheel 24 may include a solid centralportion 30 connected by clutch 23 to the shafting 18, and on which areradial pairs of threaded parallel studs 32 symmetrically arranged aboutthe axis of the fly wheel. On each pair of studs there may be ra.-dially slidably arranged a weight 34 held by centrifugal force againststops such as lnuts 36 threaded on studs 32. y

Weights 34 are shown at different radial distances to illustrate how themoment of 'inertia of the fly wheel may be changed, but of course in theoperation of the machine they will all be in the same radial position sothat the ily wheel as awhole is dynam-ically'balanced. `I vprefer toprovide central openings in the weights for radial members'38 providedwith scales 40 for setting- `the weights, and which' may' be calibratedto show the positions for different cars. In use, as will be seen,weights 34'are vadjusted radially outward for the heavier cars andinward for the lighter cars, thus enabling such an adjustment that themoment of inertia of fly wheel 24 may be the-equivalent of the linearinertiaof a car of any weight at a corresponding road speed.

While'one illustrative embodiment has 'been described in detail, it isnot my intention `to limit the scope of the invention to that particularembodiment, or otherwise than by the terms of the appended claims.

I claim:

1. Brake-testing mechanism comprising, in combination, a plurality ofmeans through which the wheels of a Vehicle may be turned against theresistance of its brakes, a common inertia means for operating thewheel-turning means, and means for selectively connecting the inertiameans to the one or more wheel turning means.

2. Brake-testing mechanism comprising, in combination, a plurality ofmeans through which the wheels of a vehicle may be turned against theresistance of its brakes, a common inertia means for operating thewheel-turning means, means for selectively connecting the inertia meansto the one or more wheel-turning means, and means for varying the momentof inertia of the inertia means.

3; A brake-testing mechanism comprising, a plurality of devices eachconstructed and arranged to turn one wheel against the resistance of itsbrake, a fly wheel, and connections between said fly wheel and saiddevices including a clutch associated with each wheel turning devicewhereby said fly wheel may be caused to selectively op-V erate one ormore of said wheel-turning devices. 4. A brake-testing mechanismcomprising, a plurality of devices eachconstructed and arranged to turnone wheel against the resistance of its brake, a fly wheel, andconnections between said fly wheel and said devices including anindependently operable clutch associated, with eachwheel-turning device.j HARRY H. SEMMES.

